- SOLID-PHASE REACTIONS OF AROMATIC AMINES WITH CARBOXYLIC ACIDS UNDER CONDITIONS OF SHEAR DEFORMATION AND HIGH PRESSURE
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Solid mixtures of carboxylic acids and aromatic amines react under shear deformation at high pressure (to 8 GPa) for form amides, in the case of ortho-phenylenediamine-substituted benzimidazoles are formed.Under these conditions the conversion rates are hundreds of thousands of times higher than when the same processes are carried out in liquid phase.The cyclization reaction is accelerated to a lesser degree than the reaction of formation of the corresponding amide.The increase of the length of the carboxylic acid radical prevents the cyclization reaction. Keywords: shear deformation, high pressure, aromatic amines, carboxylic acids, amide, benzimidazole, amidization, cyclization.
- Leont'ev, A. I.,Zharov, A. A.,Chistotina, N. P.
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- Design, synthesis, and evaluation of different scaffold derivatives against NS2B-NS3 protease of dengue virus
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The number of deaths or critical health issues is a threat in the infection caused by Dengue virus, which complicates the situation, as only symptomatic treatment is the current solution. In this regard we have targeted the dengue protease NS2B-NS3 that is responsible for the replication. The series was designed with the help of molecular modeling approach using docking protocols. The series comprised of different scaffolds viz. cinnamic acid analogs (CA1–CA11), chalcone (C1–C10) and their molecular hybrids (Lik1–Lik10), analogs of benzimidazole (BZ1-BZ5), mercaptobenzimidazole (BS1-BS4), and phenylsulfanylmethylbenzimidazole (PS1-PS4). Virtual screening of various natural phytoconstituents was employed to determine the interactions of designed analogs with the residues of catalytic triad in the active site of NS2B-NS3. We have further synthesized the selected leads. The synthesized analogs were evaluated for the cytotoxicity and NS2B-NS3 protease inhibition activity and compared with known anti-dengue natural phytoconstituent quercetin as the standard. CA2, BZ1, and BS2 were found to be more potent and efficacious than the standard quercetin as evident from the protease inhibition assay.
- Ganji, Lata R.,Gandhi, Lekha,Musturi, Venkataramana,Kanyalkar, Meena A.
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p. 285 - 301
(2020/11/19)
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- Simple inorganic base promoted C-N and C-C formation: synthesis of benzo[4,5]imidazo[1,2-a]pyridines as functional AIEgens used for detecting picric acid
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Metal-free catalyzed intermolecular tandem Michael addition/cyclization has been developed for the synthesis of benzo[4,5]imidazo[1,2-a]pyridines from α-bromocinnamaldehyde and 2-substituted benzimidazoles. The reaction promoted by a simple inorganic base displays moderate to good yields and good functional group tolerance. The optical properties of some typical products have been investigated. We found that, due to the presence of the benzene ring at the C1-position of benzo[4,5]imidazo[1,2-a]pyridines which restricts intramolecular motion, as a new type of aggregation-induced emission (AIE) luminogen (AIEgen), they show very good solid-state fluorescence with quantum yields up to 88.80%. Importantly, the AIE performance of compound3bcan be useful to detect the nitroaromatic explosive picric acid (PA) with a detection limit and quenching constant of 42.5 nM and 7.27 × 104M?M, respectively.
- Yang, Kai,Luo, Shi-He,Chen, Si-Hong,Cao, Xi-Ying,Zhou, Yong-Jun,Lin, Yan-Lan,Huo, Yan-Ping,Wang, Zhao-Yang
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supporting information
p. 8133 - 8139
(2021/10/04)
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- Preparation method 2 -substituted benzimidazole derivative
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The invention belongs to the field of fine chemical product production, and particularly relates to 2 -substituted benzimidazole derivative preparation method which comprises the following steps: (1) taking O-phenylenediamine and aldehyde as raw materials, carrying out catalytic condensation, cyclization and oxidation reaction in a eutectic solvent. (2) Water is added to the reaction system, the separated product is filtered, and the eutectic solvent is recycled. (3) After recrystallization, a target product is obtained. The method has the advantages of simple operation process, easily available raw materials, low cost, high purity of the target product and no catalyst participation, can effectively prevent isomer formation, and is beneficial to large-scale production.
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Paragraph 0053-0058
(2021/11/10)
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- s-Tetrazine-functionalized hyper-crosslinked polymers for efficient photocatalytic synthesis of benzimidazoles
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Developing green-safe, efficient and recyclable catalysts is crucial for the chemical industry. So far, organic photocatalysis has been proved to be an environmentally friendly and energy-efficient synthetic technology compared with traditional metal catalysis. As a versatile catalytic platform, hyper-crosslinked polymers (HCPs) with large surface area and high stability are easily prepared. In this report, we successfully constructed two porous HCP photocatalysts (TZ-HCPs) featurings-tetrazine units and surface areas larger than 700 m2g?1through Friedel-Crafts alkylation reactions. The rational energy-band structures and coexisting micro- and mesopores endow TZ-HCPs with excellent activities to realize the green synthesis of benzimidazoles (28 examples, up to 99% yield, 0.5-4.0 h) in ethanol. Furthermore, at least 21 iterative catalytic runs mediated by TZ-HCP1D were performed efficiently, with 96-99% yield. This study of TZ-HCPs sheds light on the wide-ranging prospects of application of HCPs as metal-free and green photocatalysts for the preparation of fine chemicals.
- An, Wan-Kai,Zheng, Shi-Jia,Zhang, Hui-Xing,Shang, Tian-Tian,Wang, He-Rui,Xu, Xiao-Jing,Jin, Qiu,Qin, Yuchen,Ren, Yunlai,Jiang, Song,Xu, Cui-Lian,Hou, Mao-Song,Pan, Zhenliang
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supporting information
p. 1292 - 1299
(2021/02/26)
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- Regioselective, Diastereoselective, and Enantioselective One-Pot Tandem Reaction Based on an in Situ Formed Reductant: Preparation of 2,3-Disubstituted 1,5-Benzodiazepine
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The 1,5-benzodiazepines are important skeletons frequently contained in medicinal chemistry. Herein, we described an unexpected tandem cyclization/transfer hydrogenation reaction for obtaining chiral 2,3-disubstituted 1,5-benzodiazepines. The enolizable aryl aldehydes were chosen as substrates to react with symmetric and unsymmetric o-phenylenediamines. The unforeseen tandem reaction occurred among many possible latent side reactions under chiral phosphoric acid catalysis and affords the corresponding products in moderate yields and regioselectivities, good diastereoselectivities, and enantiomeric ratio (up to 99:1).
- Yang, Gao-Feng,Li, Guang-Xun,Huang, Jin,Fu, Ding-Qiang,Nie, Xiao-Kang,Cui, Xin,Zhao, Jin-Zhong,Tang, Zhuo
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p. 5110 - 5119
(2021/04/12)
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- Nickel catalysed construction of benzazoles: Via hydrogen atom transfer reactions
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Herein we report a homogeneous, phosphine free, inexpensive nickel catalyst that forms a wide variety of benzazoles from alcohol and diamines by a reaction sequence of alcohol oxidation, imine formation, ring cyclization and dehydrogenative aromatization. A reversible azo/hydrazo couple, that is part of the ligand architecture steers both the alcohol oxidation and dehydrogenation of the annulated amine under fairly mild reaction conditions. Interestingly, both the alcohol oxidation and amine dehydrogenation steps are directly mediated by hydrogen atom transfer (HAT), which is greatly facilitated by the reduced ligand backbone. The kH/kD for the amine dehydrogenation step, measured at 60 °C is 5.9, fully consistent with HAT as the rate determining factor during this step. This is a unique scenario where two consecutive oxidation steps towards benzazole formation undergo HAT, which has been substantiated via kinetic studies, KIE determination and intermediate isolation. This journal is
- Adhikari, Debashis,Bains, Amreen K.,Dey, Dhananjay,Kundu, Abhishek,Yadav, Sudha
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p. 6495 - 6500
(2020/11/13)
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- Synthesis method of benzimidazole derivative
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The invention discloses a synthesis method of a benzimidazole derivative. The method comprises the following steps: o-phenylenediamine or a derivative thereof and phenylacetic acid or a derivative ofthe phenylacetic acid are used as raw materials, a composite solid catalyst is adopted, and a high-boiling-point organic solvent is taken as a reaction solvent for carrying out a reaction at 100-130 DEG C for 4-8 hours; and distillation, dissolution, neutralization, decoloration and recrystallization are carried out to obtain a benzimidazole derivative product. The method has the advantages that operation is simple, the reaction time is greatly shortened, the product color is good, the yield is high, cost is low, pollution is low, environment friendliness is achieved, and the like, and has a very good industrial production application prospect.
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Paragraph 0029; 0030
(2019/04/10)
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- Green synthesis of privileged benzimidazole scaffolds using active deep eutectic solvent
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The exploitation and use of alternative synthetic methods, in the face of classical procedures that do not conform to the ethics of green chemistry, represent an ever-present problem in the pharmaceutical industry. The procedures for the synthesis of benzimidazoles have become a focus in synthetic organic chemistry, as they are building blocks of strong interest for the development of compounds with pharmacological activity. Various benzimidazole derivatives exhibit important activities such as antimicrobial, antiviral, anti-inflammatory, and analgesic activities, and some of the already synthesized compounds have found very strong applications in medicine praxis. Here we report a selective and sustainable method for the synthesis of 1,2-disubstituted or 2-substituted benzimidazoles, starting from o-phenylenediamine in the presence of different aldehydes. The use of deep eutectic solvent (DES), both as reaction medium and reagent without any external solvent, provides advantages in terms of yields as well as in the work up procedure of the reaction.
- Gioia, Maria Luisa Di,Cassano, Roberta,Costanzo, Paola,Cano, Natividad Herrera,Maiuolo, Loredana,Nardi, Monica,Nicoletta, Fiore Pasquale,Oliverio, Manuela,Procopio, Antonio
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supporting information
(2019/08/20)
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- Additive- and Oxidant-Free Expedient Synthesis of Benzimidazoles Catalyzed by Cobalt Nanocomposites on N-Doped Carbon
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A one-pot direct synthesis of a wide range of biologically active benzimidazoles through coupling of phenylenediamines and aldehydes catalyzed by a highly recyclable nonnoble cobalt nanocomposite was developed. A broad set of benzimidazoles can be efficiently synthesized in high yields and with good functional-group tolerance under additive- and oxidant-free mild conditions. The catalyst can be easily recycled for successive uses, and the process permits gram-scale syntheses of benzimidazoles.
- Wang, Zhaozhan,Song, Tao,Yang, Yong
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supporting information
p. 319 - 324
(2019/02/12)
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- Selective synthesis of (1: H-benzo [d] imidazol-2-yl)(phenyl)methanone and quinoxaline from aromatic aldehyde and o-phenylenediamine
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We have designed a general, inexpensive, and versatile method for the synthesis of (1H-benzo[d]imidazol-2-yl)(phenyl)methanone and the formation of C-N bonds via an aromatic aldehyde and o-phenylenediamine. In the presence of N,N-dimethylformamide/sulfur, (1H-benzo[d]imidazol-2-yl)(phenyl)methanone was obtained; however, in the absence of sulfur, quinoxaline was obtained in 1,4-dioxane. A wide range of quinoxalines and (1H-benzo[d]imidazol-2-yl)(phenyl)methanones was obtained under mild conditions.
- Zhan, Zhenzhen,Ma, Haojie,Cui, Xinfeng,Jiang, Pengbo,Pu, Jinghong,Zhang, Yixin,Huang, Guosheng
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p. 5148 - 5152
(2019/06/03)
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- Reactions of 2-carbonyl- And 2-hydroxy(or methoxy)alkylsubstituted benzimidazoles with arenes in the superacid CF3SO3H. NMR and DFT studies of dicationic electrophilic species
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Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkylbenzimidazoles with arenes in the Br?nsted superacid TfOH resulted in the formation of the corresponding Friedel-Crafts reaction products, 2-diarylmethyl and 2-arylmethyl-substituted benzimidazoles, in yields up to 90%. The reaction intermediates, protonated species derived from starting benzimidazoles in TfOH, were thoroughly studied by means of NMR and DFT calculations and plausible reaction mechanisms are discussed.
- Ryabukhin, Dmitry S.,Turdakov, Alexey N.,Soldatova, Natalia S.,Kompanets, Mikhail O.,Ivanov, Alexander Yu.,Boyarskaya, Irina A.,Vasilyev, Aleksander V.
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supporting information
p. 1962 - 1973
(2019/09/03)
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- Method for preparing benzimidazole and quinazoline compounds by adopting supported nickel catalyst (by machine translation)
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The invention discloses a method for synthesizing benzimidazole and quinazoline compounds by oxidative coupling and dehydrogenation of a nitrogen-doped hierarchical porous biomass-based carbon material supported catalyst and a preparation method. The method comprises the following steps: adding o-phenylenediamine compound, alcohol, supported catalyst, toluene and potassium tert-butoxide as a solvent, carrying out reaction under 50~150 °C conditions, carrying out reaction 4~24 hours, cooling to room temperature, filtering the reaction liquid, and obtaining a benzimidazole compound or quinazoline compound. The method adopts "one-pot method" preparation, the intermediate can be separated and purified, energy consumption can be reduced, and the efficiency. (by machine translation)
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Paragraph 0054-0056; 0057; 0059
(2019/07/16)
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- An efficient NaHSO3-promoted protocol for chemoselective synthesis of 2-substituted benzimidazoles in water
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An efficient protocol for chemoselective synthesis of 2-substituted benzimidazoles from a variety of aliphatic/aromatic/ heteroaryl aldehydes and o-phenylenediamine derivatives promoted by NaHSO3 in water had been developed. The amount of NaHSO3 had a great effect on the reaction selectivity of 2-substituted benzimidazole and 1,2-disubstituted benzimidazole when the reaction was carried out in water. When the amount of the NaHSO3 was more than 11 equivalents, the 2-substituted benzimidazole could be highly selectively formed as the sole product. NaHSO3 was firstly reacted with aldehyde to form the aldehyde sodium bisulfite, which reacted with o-phenylenediamine to form the 2-substituted benzimidazole and inhibited the formation of 1,2-disubstituted benzimidazole. This protocol solved the poor selectivity problem appearing in traditional method when cyclocondensation between o-phenylenediamine and aldehydes. The method also had advantage of simple work up by filtrating the single 2-substituted benzimidazole precipitates from reaction mixture at the end of the reaction without further purification. In addition, the method was applicable to both electron-rich and electron-poor starting materials, which was successfully used for synthesizing nine novel 2-substituted benzimidazole derivatives containing a 1,2,3-triazole moiety. They were characterized by NMR, IR and HRMS spectrum. Moreover, this method had been applied to a large scale synthesis of 2-substituted benzimidazole derivatives.
- Jiang, Yu-Qin,Jia, Shu-Hong,Li, Xi-Yong,Sun, Ya-Min,Li, Wei,Zhang, Wei-Wei,Xu, Gui-Qing
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p. 1265 - 1276
(2019/01/28)
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- I2/TBHP promoted oxidative C–N bond formation at room temperature: Divergent access of 2-substituted benzimidazoles involving ring distortion
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A new ‘one pot’ tandem synthesis of 2-substituted benzimidazoles has been developed from 2-aminobenzyl alcohol/2-aminobenzamide and different coupling partners (nitriles, aldehydes and 1,3-diketones) via iodine and TBHP promoted oxidative ring contraction. The present strategy involves sequential C–N bond formation, cyclization, subsequent ring contraction and dehydrogenation to afford various medicinally important benzimidazole derivatives in moderate to good yields. This operationally simple synthetic approach proceeds at room temperature under base-free condition, broadly applicable to a wide array of nitriles and aldehydes bearing oxidation prone functional groups and noteworthy to mention that various acyclic 1,3-diketones undergo selective C–C bond cleavage leading to 2-alkyl benzimidazoles under mild condition.
- Saha, Moumita,Das, Asish R.
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supporting information
p. 2520 - 2525
(2018/05/31)
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- Direct Synthesis of Benzimidazoles by Dehydrogenative Coupling of Aromatic Diamines and Alcohols Catalyzed by Cobalt
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Herein, we present the base-metal-catalyzed dehydrogenative coupling of primary alcohols and aromatic diamines to selectively form functionalized 2-substituted benzimidazoles, liberating water and hydrogen gas as the sole byproducts. The reaction is catalyzed by pincer complexes of Earth-abundant cobalt under base-free conditions.
- Daw, Prosenjit,Ben-David, Yehoshoa,Milstein, David
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p. 7456 - 7460
(2017/11/10)
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- Discovery of benzimidazole derivatives as modulators of mitochondrial function: A potential treatment for Alzheimer's disease
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In this study, we designed a library of compounds based on the structures of well-known ligands of the 18 kDa translocator protein (TSPO), one of the putative components of the mPTP. We performed diverse mitochondrial functional assays to assess their ability to restore cells from Aβ-induced toxicity in vitro and in vivo. Among tested compounds, compound 25 effectively improved cognitive function in animal models of AD. Given the excellent in vitro and in vivo activity and a favorable pharmacokinetic profile of compound 25, we believe that it can serve as a promising lead compound for a potential treatment option for AD.
- Kim, TaeHun,Yang, Ha Yun,Park, Beoung Gun,Jung, Seo Yun,Park, Jong-Hyun,Park, Ki Duk,Min, Sun-Joon,Tae, Jinsung,Yang, Hyejin,Cho, Suengmok,Cho, Sung Jin,Song, Hyundong,Mook-Jung, Inhee,Lee, Jiyoun,Pae, Ae Nim
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p. 1172 - 1192
(2016/11/23)
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- Dehydrogenative synthesis of benzimidazoles under mild conditions with supported iridium catalysts
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Solid supported iridium catalysts, which show excellent activity for the dehydrogenative synthesis of benzimidazoles from primary alcohols and phenylenediamine derivatives under mild reaction conditions, were developed. Among the catalysts examined, the titania-supported iridium catalyst showed the highest activity, and benzimidazole derivatives were selectively produced at temperatures of 80°C or higher. For example, the reaction of phenylenediamine (1a) with benzyl alcohol (2a) in the presence of Ir(1.0 wt%)/TiO2 (1.0 mol%, towards 1a) at 120°C selectively gave 2-phenylbenzimidazole (3aa) in 80% yield after 6 h and over 90% yield after 18 h. A high turnover number (TON) of more than 800 was achieved in the reaction at a higher substrate-to-catalyst ratio. Reduction of the catalysts under a hydrogen atmosphere at around 500 to 600°C is essential for their significant activity. Characterization of the catalysts by gas adsorption, XRD, XPS, H2-TPR, TEM, and XAFS techniques revealed that highly-dispersed nanoparticles of the iridium(0) species (ca. 1 to 2 nm in diameter) formed on TiO2 are responsible for the catalysis. The catalysts could be recycled without a significant loss of activity, and the leaching of the iridium species into the solution during the catalytic runs was negligible, which suggests that the present catalysts would be excellent from both environmental and practical perspectives.
- Tateyama, Keisuke,Wada, Kenji,Miura, Hiroki,Hosokawa, Saburo,Abe, Ryu,Inoue, Masashi
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p. 1677 - 1684
(2016/04/05)
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- Exploration of 2-benzylbenzimidazole scaffold as novel inhibitor of NF-κB
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For finding the novel inhibitor of nuclear factor κB activity, a series of benzimidazole derivatives were rationally designed, synthesized and systematically studied for their in vitro activities against LPS induced NF-κB inhibition in RAW 264.7 cells using the SEAP assay based on the flexible chalcone JSH ((E)-1-(2-hydroxy-6-(isopentyloxy)phenyl)-3-(4-hydroxy phenyl)prop-2-en-1-one) which was previously reported. Although most of the benzimidazole derivatives showed strong inhibitory activity in low micromolar potency, 2-(4-methoxybenzyl)-1H-benzo[d]imidazole (3m; IC50 = 1.7 μM) and 2-(2-methoxybenzyl)-1H-benzo[d]imidazole (3n; IC50 = 2.4 μM) showed the best inhibition. The structure activity relationship revealed that 2-benzylbenzimidazole scaffold with hydrogen bonding acceptor on phenyl ring appears as a pharmacophore.
- Boggu, PullaReddy,Venkateswararao, Eeda,Manickam, Manoj,Kwak, Dajin,Kim, Youngsoo,Jung, Sang-Hun
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p. 1872 - 1878
(2016/04/05)
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- Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf)3 catalyst in the reaction selectivity
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An improved and greener protocol for the synthesis of benzimidazole derivatives, starting from o-phenylenediamine, with different aldehydes is reported. Double-condensation products were selectively obtained when Er(OTf)3 was used as the catalyst in the presence of electron-rich aldehydes. Conversely, the formation of mono-condensation products was the preferred path in absence of this catalyst. One of the major advantages of these reactions was the formation of a single product, avoiding extensive isolation and purification of products, which is frequently associated with these reactions. Theoretical calculations helped to understand the different reactivity established for these reactions. Thus, we found that the charge density on the oxygen of the carbonyl group has a significant impact on the reaction pathway. For instance, electron-rich aldehydes better coordinate to the catalyst, which favours the addition of the amine group to the carbonyl group, therefore facilitating the formation of double-condensation products. Reactions with aliphatic or aromatic aldehydes were possible, without using organic solvents and in a one-pot procedure with short reaction time (2-5 min), affording single products in excellent yields (75-99%). This convenient and eco-friendly methodology offers numerous benefits with respect to other protocols reported for similar compounds.
- Herrera Cano, Natividad,Uranga, Jorge G.,Nardi, Mónica,Procopio, Antonio,Wunderlin, Daniel A.,Santiago, Ana N.
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supporting information
p. 2410 - 2419
(2016/12/07)
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- Decarboxylative Coupling of α-Keto Acids with ortho-Phenylenediamines Promoted by an Electrochemical Method in Aqueous Media
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An electrochemical method for the decarboxylative coupling of α-keto acids with ortho-phenylenediamines was developed. The reaction proceeded smoothly in aqueous solution under air and metal catalyst-free conditions to afford 2-substituted benzimidazoles in good yields. Benzothiazoles could also be synthesized by this protocol. (Figure presented.) .
- Wang, Hai-Bin,Huang, Jing-Mei
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supporting information
p. 1975 - 1981
(2016/07/06)
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- Copper(II)-Catalyzed Oxidative Cross-Coupling of Anilines, Primary Alkyl Amines, and Sodium Azide Using TBHP: A Route to 2-Substituted Benzimidazoles
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Copper(II)-catalyzed oxidative cross-coupling of anilines, primary alkyl amines, and sodium azide is described in the presence of TBHP at moderate temperature. This one-pot multicomponent protocol involves a domino C-H functionalization, transimination, ortho-selective amination, and a cyclization sequence. The broad substrate scope and functional group compatibility are the significant practical features. The protocol can be extended to the coupling of benzyl alcohols with moderate yields.
- Mahesh, Devulapally,Sadhu, Pradeep,Punniyamurthy, Tharmalingam
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p. 3227 - 3234
(2016/05/19)
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- Acceptorless dehydrogenative synthesis of benzothiazoles and benzimidazoles from alcohols or aldehydes by heterogeneous Pt catalysts under neutral conditions
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Abstract Pt/Al2O3 and Pt/TiO2 were effective catalysts for the synthesis of 2-substituted benzothiazoles and benzimidazoles from 2-aminothiophenol and 1,2-phenylenediamine with alcohols or aldehydes under acceptor-free and additive-free conditions.
- Chaudhari, Chandan,Siddiki, S.M.A. Hakim,Shimizu, Ken-Ichi
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p. 4885 - 4888
(2015/07/28)
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- Expedient synthesis of benzimidazoles using amides
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In the present report an efficient, rapid, facile and inexpensive route for the synthesis of benzimidazoles using 1,2-arylenediamines and N,N-dimethylformamide in acidic medium under thermal/microwave condition is developed. This reaction was further explored with the different amides to afford a library of 2-substituted benzimidazoles. The advantage of the present synthetic method includes shorter reaction time, easy work up and excellent yields without using catalysts.
- Kattimani, Pramod P.,Kamble, Ravindra R.,Meti, Gangadhar Y.
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p. 29447 - 29455
(2015/04/14)
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- Trichloroisocyanuric Acid/Triphenylphosphine-Mediated Synthesis of Benzimidazoles, Benzoxazoles, and Benzothiazoles
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A new and efficient method for preparation of benzimidazoles, benzoxazoles, and benzothiazoles from reactions of different carboxylic acids with o-phenylenediamine, o-aminophenol, and o-aminothiophenol in the presence of triphenylphosphine/trichloroisocyanuric acid system is presented. The desired products have been characterised on the basis of spectral (infrared, NMR, mass spectrometry) data, and the mechanism of their formation is proposed. The remarkable advantages are the inexpensive and readily available reagent, simple procedure, mild conditions, and good-to-excellent yields.
- Rezazadeh, Soodabeh,Akhlaghinia, Batool,Razavi, Nasrin
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p. 145 - 155
(2015/05/05)
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- Benzimidazoles and benzoxazoles via the nucleophilic addition of anilines to nitroalkanes
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PPA-induced umpolung triggers efficient nucleophilic addition of unactivated anilines to nitroalkanes to produce N-hydroxyimidamides. The latter undergo sequential acid-promoted cyclocondensation with ortho-OH or ortho-NHR moieties to afford benzoxazoles
- Aksenov, Alexander V.,Smirnov, Alexander N.,Aksenov, Nicolai A.,Bijieva, Asiyat S.,Aksenova, Inna V.,Rubin, Michael
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p. 4289 - 4295
(2015/04/14)
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- BENZIMIDAZOLE DERIVATIVES AS MITOCHONDRIAL FUNCTION MODULATORS
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Provided are a benzimidazole derivative modulating mitochondrial functions and having pharmaceutical activity as a neuro-protective agent, and a pharmaceutical composition including the compound as an active ingredient.
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Paragraph 0199-0200
(2014/05/07)
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- Metal-free aerobic oxidation of benzazole derivatives
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2-Benzyl benzothiazoles and benzimidazoles are easily oxidized under air and basic conditions to give the corresponding ketones in good yields. The use of palladium acetate as a catalyst has little effect and even gives, in some cases, much lower yields.
- Dos Santos, Aurelie,El Kaim, Laurent,Grimaud, Laurence
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supporting information
p. 3282 - 3287
(2013/06/05)
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- Polystyrene-supported pyridinium chloroaluminate ionic liquid as a new heterogeneous Lewis acid catalyst for selective synthesis of benzimidazoles
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Polystyrene-supported pyridinium chloroaluminate ionic liquid was prepared from the reaction of a Merrifield resin with pyridine followed by reaction with aluminium chloride. This catalyst was used as a new chemoselective Lewis acid catalyst for the exclusive synthesis of 2-substituted benzimidazoles from the reaction of aldehydes with o-phenylenediamines. The catalyst was stable (as a benchtop catalyst) and could easily be recovered and reused without appreciable change in its efficiency.
- Boroujeni, Kaveh Parvanak,Zhianinasab, Ashkan,Jafarinasab, Mina
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p. 155 - 164
(2013/08/25)
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- CuO nano-particles supported on silica, a new catalyst for facile synthesis of benzimidazoles, benzothiazoles and benzoxazoles
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A facile synthetic route for benzimidazoles, benzothiazoles and benzoxazoles comprising the reaction of corresponding o-phenylenediamine, o-aminothiophenol and o-aminophenol with various aldehydes using silica supported nano-copper (II) oxide as a catalyst has been described. The catalyst exhibited clean reaction profile with excellent yields in a short reaction time. The catalyst can be recycled effectively after use.
- Inamdar, Suleman M.,More, Vinod K.,Mandal, Sisir K.
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p. 579 - 583
(2013/02/23)
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- Cu(I)-catalyzed synthesis of 2-substituted benzimidazoles from 2-iodoanilines and amides
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A novel and efficient approach to the synthesis of 2-substituted benzimidazoles has been developed via CuI/DMEDA-catalyzed coupling reaction and post-cyclization with glacial acetic acid from readily available 2-iodoanilines and amides. This method is suitable for the construction of a variety of benzimidazoles in moderate to good yields under short reaction times. A novel and efficient approach to the synthesis of 2-substituted benzimidazoles has been developed via CuI/DMEDA-catalyzed coupling reaction and post-cyclization with glacial acetic acid from readily available 2-iodoanilines and amides. This method is suitable for the construction of a variety of benzimidazoles in moderate to good yields under short reaction times. Copyright
- Yuan, Hua,Chen, Yongxin,Song, Jinli,Chen, Chunxia,Chen, Baohua
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supporting information
p. 1247 - 1249
(2013/11/06)
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- Microwave-assisted synthesis of 2-substituted 1h-benzo[d]imidazoles and their antifungal activities in vitro
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An efficient and novel microwave-assisted synthesis of 1H-benzo[d]imidazole derivatives via nitriles and o-phenyldiamines in the presence of polyphosphoric acid (PPA) and phosphoric acid is described. This method provides several advantages such as commercially high availabilities of starting materials, short reaction times, high yields and a simple workup procedure. Systematically antifungal biological tests showed 3f was most promising candidate against six phytopathogenic fungi.
- Zhang, Tao,Huang, Liang-Zhu,Wu, Jia,Lu, Dong,Ma, Bo-Lin,Du, Zhen-Ting
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p. 1545 - 1552
(2013/07/26)
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- Synthesis of benzimidazoles by PIDA-promoted direct C(sp2)-H imidation of N-arylamidines
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A metal-free synthesis of diversified benzimidazoles from N-arylamidines through a phenyliodine(III) diacetate (PIDA) promoted intramolecular direct C(sp2)-H imidation has been developed. The reaction proceeds smoothly at 0 °C or ambient temperature to provide the desired products in good to excellent yields. The synthesis of 2-alkyl- or 2-alkyl-fused benzimidazoles, which are generally inaccessible by similar Pd- or Cu-catalyzed approaches, can also be achieved. Copyright
- Huang, Jinbo,He, Yimiao,Wang, Yong,Zhu, Qiang
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supporting information
p. 13964 - 13967
(2013/01/15)
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- The efficient o-benzenedisulfonimide catalysed synthesis of benzothiazoles, benzoxazoles and benzimidazoles
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O-Benzenedisulfonimide has been used to efficiently catalyse the reaction between 2-aminothiophenol, 2-aminophenol, o-phenylenediamine and various ortho esters (28 examples; average yield 90%) or aldehydes (17 examples; average yield 72%) giving the corresponding benzofused azoles in excellent yields. Reaction conditions were very simple. In addition, other carboxylic acid derivatives have been tested and gave good results. The catalyst was easily recovered and reused. ARKAT-USA, Inc.
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano
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p. 262 - 279
(2013/02/25)
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- Benzazoles from aliphatic amines and o -amino/mercaptan/hydroxyanilines: Elemental sulfur as a highly efficient and traceless oxidizing agent
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A novel remarkably simple solvent-free and catalyst-free synthesis of benzazoles from alkylamines and o-hydroxy/amino/mercaptan anilines using elemental sulfur as traceless oxidizing agent has been developed.
- Nguyen, Thanh Binh,Ermolenko, Ludmila,Dean, William A.,Al-Mourabit, Ali
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supporting information
p. 5948 - 5951
(2013/02/23)
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- A general approach to substituted benzimidazoles and benzoxazoles via heterogeneous palladium-catalyzed hydrogen-transfer with primary amines
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The synthesis of benzimidazoles starting from o-phenylenediamines and amines in the presence of palladium on charcoal as catalyst is reported. Under microwave dielectric heating it is possible to use a tertiary, a secondary, and even a primary amine as the substrate for a palladium-mediated process to get 2-substituted or 1,2-disubstituted benzimidazoles, depending on the nature of the o-phenylenediamine employed. Primary amines are the most suitable reagents for the atom economy of the overall process that resulted to be general as several different substituted benzimidazoles were obtained in good yield. Benzoxazoles can be also prepared starting from primary amines and o-aminophenol. The reaction is also highly selective as no (poly)-alkylated phenylenediamines or cross-contaminated benzimidazoles are obtained starting from N-monoalkylphenylenediamines. This behavior was interpreted as a scarce aptitude to dehydrogenation of the methylene bonded to the aromatic NH of N-alkylarylamines. The experiments carried out consent to draw an almost complete picture of the reaction pathways occurring during the process. The catalyst can be recycled several times and, although far from optimal performances, catalyst TON=90 is encouraging for further large-scale optimization protocols. In addition, the palladium on charcoal-catalyzed microwave-assisted reaction of o-phenylenediamine gives de-alkylation of tertiary amines and transformation into the secondary ones. Copyright
- Pizzetti, Marianna,De Luca, Elisa,Petricci, Elena,Taddei, Maurizio,Porcheddu, Andrea
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supporting information
p. 2453 - 2464,12
(2012/12/12)
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- A general approach to substituted benzimidazoles and benzoxazoles via heterogeneous palladium-catalyzed hydrogen-transfer with primary amines
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The synthesis of benzimidazoles starting from o-phenylenediamines and amines in the presence of palladium on charcoal as catalyst is reported. Under microwave dielectric heating it is possible to use a tertiary, a secondary, and even a primary amine as the substrate for a palladium-mediated process to get 2-substituted or 1,2-disubstituted benzimidazoles, depending on the nature of the o-phenylenediamine employed. Primary amines are the most suitable reagents for the atom economy of the overall process that resulted to be general as several different substituted benzimidazoles were obtained in good yield. Benzoxazoles can be also prepared starting from primary amines and o-aminophenol. The reaction is also highly selective as no (poly)-alkylated phenylenediamines or cross-contaminated benzimidazoles are obtained starting from N-monoalkylphenylenediamines. This behavior was interpreted as a scarce aptitude to dehydrogenation of the methylene bonded to the aromatic NH of N-alkylarylamines. The experiments carried out consent to draw an almost complete picture of the reaction pathways occurring during the process. The catalyst can be recycled several times and, although far from optimal performances, catalyst TON=90 is encouraging for further large-scale optimization protocols. In addition, the palladium on charcoal-catalyzed microwave-assisted reaction of o-phenylenediamine gives de-alkylation of tertiary amines and transformation into the secondary ones. Copyright
- Pizzetti, Marianna,De Luca, Elisa,Petricci, Elena,Porcheddu, Andrea,Taddei, Maurizio
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supporting information
p. 2453 - 2464
(2013/01/14)
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- KF/Al2O3: An efficient solid heterogeneous base catalyst in one-pot synthesis of benzimidazoles and bis-benzimidazoles at room temperature
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KF/Al2O3 is an efficient solid heterogeneous base catalyst in the one-pot synthesis of 2-substituted benzimidazoles and 2,2′-disubstituted bis-benzimidazoles from 1,2-phenylenediamines or 3,3′-diaminobenzidines and acid chlorides, anhydrides, and esters at room temperature. Springer-Verlag 2011.
- Khalili, Saeed Bahadori,Sardarian, Ali Reza
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experimental part
p. 841 - 846
(2012/08/07)
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- Boric acid-catalyzed direct condensation of carboxylic acids with benzene-1,2-diamine into benzimidazoles
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The applicability of boric acid catalysis for the direct condensation of carboxylic acids with benzene-1,2-diamine to give 2-substituted benzimidazoles was investigated. It was found that catalytic amounts (5-10 mol-%) of boric acid efficiently promote the cyclocondensation of aliphatic carboxylic acids in refluxing toluene. In addition, the relatively neutral conditions allow the use of acid-sensitive substrates and give rise to specific transformations and selectivities that are not observed with some classical methods. Benzoic acids were found to be less reactive than aliphatic acids and thus require refluxing xylene for better efficiency. Phenylboronic acid was found to be inactive as a catalyst due to its rapid consumption by condensation with benzene-1,2-diamine to give a 2-phenylbenzodiazaborole. Copyright
- Maras, Nenad,Kocevar, Marijan
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experimental part
p. 1860 - 1874
(2011/12/02)
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- Synthesis of benzimidazoles by phosphine-mediated reductive cyclisation of ortho-nitro-anilides
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Heating ortho-nitro-anilides 1-3 and 2-methyl-N-(3-nitropyridin-2-yl) propanamide (5) with 4 equiv. of a phosphine led to the 2-substituted benzimidazoles 6-8 and to the imidazo[4,5-b]pyridine 10, respectively, in yields between 45 and 85%. Heating 1 with (EtO)3P effected cyclisation and N-ethylation, leading to the 1-ethylbenzimidazole 6b. The slow cyclisation of the N-pivaloylnitroaniline 2b allowed isolation of the intermediate phosphine imide 11 that slowly transformed into the 1H-benzimidazole 7b. The structure of 11 was established by crystal-structure analysis. While the N-methylated ortho-nitroacetanilide 3 cyclised to the 1,2-dimethyl-1H-benzimidazole (8), the 2-methylpropananilide 4 was transformed into 1-methyl-3-(1-methylethyl)-2H- benzimidazol-2-one (9).
- Duchek, Jan,Vasella, Andrea
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experimental part
p. 977 - 986
(2011/08/05)
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- Room temperature synthesis of benzimidazole derivatives using reusable cobalt hydroxide (II) and cobalt oxide (II) as efficient solid catalysts
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Here we demonstrate the synthesis of benzimidazoles through the coupling of 1,2-phenylenediamine with aldehydes by using Co(OH)2 and similarly CoO(II) as efficient solid catalysts in ethanol at room temperature. The Co(OH)2 solid catalyst gave better yields (82-98%) in short reaction times (4-7 h) than CoO(II) catalyst (80-94%, 6-9 h). These commercially available cheap catalysts are more active than many reported expensive heterogeneous catalysts.
- Adharvana Chari, Murugulla,Shobha, Donthabhakthuni,Sasaki, Takehiko
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experimental part
p. 5575 - 5580
(2011/11/06)
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- Mild and highly efficient protocol for the synthesis of benzimidazoles using samarium triflate [Sm(OTf)3]
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One-pot synthesis of benzimidazole compounds from ortho-phenylenediamine and a variety of aldehydes was developed under mild reaction conditions. All the reactions were carried out in the presence of samarium triflate (10mol%) in acetonitrile at room temperature. Copyright Taylor & Francis Group, LLC.
- Narsaiah, A. Venkat,Reddy, A. Ramesh,Yadav
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experimental part
p. 262 - 267
(2011/03/20)
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- Microwave assisted synthesis of 1,3,4-oxadiazoles carrying benzimidazole moiety and their antimicrobial properties
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A new series of 2-substituted-l-[(5-substituted phenyl-1,3,4- oxadiazol-2-yl)methyl]-1H-benzimidazole have been synthesized. The structures of new compounds have been confirmed by spectral and analytical data. The newly synthesized compounds have been evaluated for their antifungal and antibacterial activity.
- Gowda, Janardhana,Khadar,Kalluraya, Balakrishna,Kumari, Nalilu Suchetha
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experimental part
p. 1130 - 1134
(2010/10/21)
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- Synthesis, characterization and in vivo anthelmintic activity of some novel N-Mannich bases of benzimidazoles
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As a part of ongoing efforts towards finding novel anthelmintic agents, N-Mannich bases of benzimidazole were obtained by condensation of substituted secondary amines and aldehyde in ethanol. These compounds were identified on the basis of melting point range, Rf values, elemental analysis, IR and 1H NMR spectral analysis. The synthetic work is fruitless without performing biological activities, so the newly synthesized compounds were screened for pharmacological activity. Anthelmintic activity was carried out against Eudrilus species of earthworms.
- Murti, Yogesh,Arora, Rashmi,Pathak, Devender
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experimental part
p. 627 - 631
(2011/08/05)
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- Facile and efficient synthesis of benzoxazoles and benzimidazoles: The application of Hantzsch ester 1,4-dihydropyridines in reductive cyclization reactions
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Both benzoxazole and benzimidazole are common heterocyclic scaffolds in biologically active and medicinally significant compounds. Reductive cyclization of ortho-substituted nitrobenzene derivatives provides an attractive route to benzoxazole or benzimidazole ring formation. Unfortunately, only a few synthetic methods by reductive cyclization ofortho-nitro compounds have been reported and the yields are rather low. In continuation of the development of biomimetic reductants in synthetically useful organic transformations, Hantzsch ester 1,4-dihydropyridine (HEH), analogues of NAD(P)H, has attracted a considerable amount of attention. Hence, we wish to report that benzoxazoles and benzimidazoles can be efficiently synthesized by the reaction of ortho-substituted nitrobenzene derivatives with HEH catalyzed by Pd/C. A range of functionalized ortho-nitrophenyl esters or ortho-nitrophenyl amides were efficiently reduced by HEH and cyclized to the corresponding benzoxazoles or benzimidazoles. Especially, working in the presence of the same substituents, benzimidazoles could be obtained in higher yields with respect to the corresponding benzoxazoles. Moreover, in the present work, the recycling of Pd/C was studied and was shown to maintain its high catalytic activity over five runs. On the basis of our experimental results and DFT calculations, a plausible reaction mechanism was proposed. Copyright
- Xing, Rui-Guang,Li, Ya-Nan,Liu, Qiang,Meng, Qing-Yuan,Li, Jing,Shen, Xiao-Xia,Liu, Zhengang,Zhou, Bo,Yao, Xiaojun,Liu, Zhong-Li
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experimental part
p. 6627 - 6632
(2011/03/17)
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- Nanoporous aluminosilicate catalyst with 3D cage-type porous structure as an efficient catalyst for the synthesis of benzimidazole derivatives
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Herein we demonstrate for the first time, the synthesis of benzimidazoles through the coupling of aldehydes with o-phenylenediamine by using highly acidic nanoporous aluminosilicate with 3D structure and cage-type pores as the catalyst. The catalyst resulted in excellent yields in short reaction times presumably due to its high acidity, large pore diameter, high surface area, and cage-type 3D porous structure.
- Chari, Murugulla A.,Shobha,Kenawy, El-Refaie,Al-Deyab, Salem S.,Reddy, B.V. Subba,Vinu, Ajayan
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experimental part
p. 5195 - 5199
(2010/11/05)
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- Synthesis of benzazoles by hydrogen-transfer catalysis
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Transition-metal-catalyzed hydrogen-transfer reactions have been used for the conversion of alcohols into benzimidazoles and aldehydes into benzoxazoles and benzothiazoles.
- Blacker, A. John,Farah, Mohamed M.,Hall, Michael I.,Marsden, Stephen P.,Saidi, Ourida,Williams, Jonathan M. J.
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supporting information; experimental part
p. 2039 - 2042
(2009/09/08)
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- One-pot synthesis of functionalized benzimidazoles and 1H-pyrimidines via cascade reactions of o-aminoanilines or naphthalene-1,8-diamine with alkynes and p-tolylsulfonyl azide
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A one-pot synthesis of functionalized benzimidazoles and 1H-pyrimidines via the cascade reactions of o-aminoanilines or naphthalene-1,8-diamine with terminal alkynes and p-tolylsulfonyl azide is reported. The protocol is efficient and general. Georg Thiem
- She, Jin,Jiang, Zheng,Wang, Yanguang
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experimental part
p. 2023 - 2027
(2010/03/04)
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- Assembly of substituted 1H-benzimidazoles and 1,3-dihydrobenzimidazol-2- ones via CuI/L-proline catalyzed coupling of aqueous ammonia with 2-iodoacetanilides and 2-iodophenylcarbamates
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(Chemical Equation Presented) CuI/L-proline catalyzed coupling of aqueous ammonia with 2-iodoacetanilides and 2-iodophenylcarbamates affords the aryl amination products at room temperature, which undergo in situ additive cyclization under acidic conditions or heating to give substituted 1H-benzimidazoles and 1,3-dihydrobenzimidazol-2-ones, respectively. A wide range of functional groups including ketone, nitro, iodo, bromo, and ester are tolerated under these reaction conditions, providing these heterocycles with great diversity.
- Diao, Xiaoqiong,Wang, Yuji,Jiang, Yongwen,Ma, Dawei
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experimental part
p. 7974 - 7977
(2010/02/28)
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- Comparative studies on conventional and microwave synthesis of some benzimidazole, benzothiazole and indole derivatives and testing on inhibition of hyaluronidase
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We have synthesized twelve 2-substituted benzimidazole, benzothiazole and indole derivatives using on both microwave irradiation and conventional heating methods. The microwave method was observed to be more beneficial as it provides an increase of yield from 3% to 113% and a 95 to 98 % reduction in time. All compounds were tested by a stains-all assay at pH 7 and by a Morgan-Elson assay at pH 3.5 for hyaluronidase inhibitory activity at a concentration of 100 μM. The most potent compound was 2-(4-hydroxyphenyl)-3-phenylindole (12) with an IC50 value of 107 μM at both pH 7 and 3.5.
- Algul, Oztekin,Kaessler, Andre,Apcin, Yagmur,Yilmaz, Akin,Jose, Joachim
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p. 736 - 748
(2008/09/20)
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- Sulfonic acid functionalized silica as an efficient heterogeneous recyclable catalyst for one-pot synthesis of 2-substituted benzimidazoles
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(Chemical Equation Presented) An efficient one-pot synthesis of 2-substituted benzimidazoles from o-phenylenediamine and aldehydes in the presence of sulfonic acid functionalized silica at room temperature is reported.
- Das, Biswanath,Kanth, Boddu Shashi,Reddy, Kongara Ravinder,Kumar, Avula Satya
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experimental part
p. 1499 - 1502
(2009/04/14)
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